Abstract: A wrench construction wherein the wrench can be formed from an injection molded plastic material, and includes a handle and respective first and second head members extending from the ends of the handle. One of the head members is larger than the other, and each head member defines at least a part of a regular polygon adapted to be drivingly engageable and disengageable with a fastener element, such as a nut or bolt. Each of the head members and the handle is of generally U-shaped cross-section and includes a plurality of transverse stiffner members that extend from the base of the U and across the legs thereof to provide desired strength and rigidity of the structure at light weight.